title: Cardiac-specific overexpression of insulin-like growth factor I (IGF-1) rescues lipopolysaccharide-induced cardiac dysfunction and activation of stress signaling in murine cardiomyocytes.
abstract: Lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria, plays a key role in cardiac dysfunction in sepsis. Low circulating levels of insulin-like growth factor 1 (IGF-1) are found in sepsis, although the influence of IGF-1 on septic cardiac defect is unknown. This study was designed to examine the impact of IGF-1 on LPS-induced cardiac contractile and intracellular Ca2+ dysfunction, activation of stress signal and endoplasmic reticulum (ER) stress. Mechanical and intracellular Ca2+ properties were examined in cardiomyocytes from Fast Violet B and cardiac-specific IGF-1 overexpression mice treated with or without LPS (4 mg kg(-1), 6 h). Reactive oxygen species (ROS), protein carbonyl formation and apoptosis were measured. Activation of mitogen-activated protein kinase pathways (p38, c-jun N-terminal kinase [JNK] and extracellular signal-related kinase [ERK]), ER stress and apoptotic markers were evaluated using Western blot analysis. Our results revealed decreased peak shortening and maximal velocity of shortening/relengthening and prolonged duration of relengthening in LPS-treated Fast Violet B cardiomyocytes associated with reduced intracellular Ca2+ decay. Accumulation of ROS protein carbonyl and apoptosis were elevated after LPS treatment. Western blot analysis revealed activated p38 and JNK, up-regulated Bax, and the ER stress markers GRP78 and Gadd153 in LPS-treated mouse hearts without any change in ERK and Bcl-2. Total protein expression of p38, JNK, and ERK was unaffected by either LPS or IGF-1. Interestingly, these LPS-induced changes in mechanical and intracellular Ca2+ properties, ROS, protein carbonyl, apoptosis, stress signal activation, and ER stress markers were effectively ablated by IGF-1. In vitro LPS exposure (1 microg mL(-1)) produced cardiomyocyte mechanical dysfunction reminiscent of the in vivo setting, which was alleviated by exogenous IGF-1 (50 nM). These data collectively suggested a beneficial of IGF-1 in the management of cardiac dysfunction under sepsis.
authors.affiliation: Department of Cardiology, Shandong Provincial Hospital, Shandong University, Jinan, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhao
authors.forename: Subat
authors.initials: S
authors.lastname: Turdi
authors.forename: Feng
authors.initials: F
authors.lastname: Dong
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Xiao
authors.forename: Guohai
authors.initials: G
authors.lastname: Su
authors.forename: Xinglei
authors.initials: X
authors.lastname: Zhu
authors.forename: Glenda I
authors.initials: GI
authors.lastname: Scott
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717248:Hspa5 protein, mouse; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D007334:Insulin-Like Growth Factor I; D053148:Caspase 3; D002118:Calcium